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Re: [AtkinBoats] Shaft angle

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  • Kenneth Grome
    ... It will more than likely create a more efficient propulsion system. The nearer to horizontal the shaft, the more efficient the propulsion system. Atkin
    Message 1 of 6 , Apr 3, 2008
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      > The propeller shaft in River Belle has an upward
      > angle of about 6°. It would be convenient to have
      > that nearer horizontal - does anyone have any
      > thoughts about what effect that change might have?


      It will more than likely create a more efficient propulsion system. The
      nearer to horizontal the shaft, the more efficient the propulsion
      system.

      Atkin probably raised the forward end because he may not have been able
      to install a truly horizontal shaft when using the engine /
      transmission he specified. This is my guess anyways.

      Sincerely,
      Ken Grome
      Bagacay Boatworks
      www.bagacayboatworks.com
    • sals_dad
      ... able ... That would be my guess, as well. I am still struggling with how to get a horizontal shaft in Rescue Minor. The Kubota is just perched too high
      Message 2 of 6 , Apr 4, 2008
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        > > The propeller shaft in River Belle has an upward
        > > angle of about 6°. It would be convenient to have
        > > that nearer horizontal - does anyone have any
        > > thoughts about what effect that change might have?
        >
        > Atkin probably raised the forward end because he may not have been
        able
        > to install a truly horizontal shaft when using the engine /
        > transmission he specified. This is my guess anyways.

        That would be my guess, as well. I am still struggling with how to get
        a horizontal shaft in Rescue Minor. The Kubota is just perched too
        high up on its oil pan.

        But, that said, be careful messing with the geometry - Atkin probably
        took the angle into account when desingning the hull and tunnel.

        Sal's Dad
      • Tom Hesselink
        Alan, The first question is why do you want to lower the shaft angle? Is it to get the motor under the cabin sole? That seems unlikely from what sketchs I
        Message 3 of 6 , Apr 4, 2008
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          Alan, The first question is why do you want to lower the shaft
          angle? Is it to get the motor under the cabin sole? That seems
          unlikely from what sketchs I can see on the web. Once the motor
          pojects into the cabin- it usually dosent matter how high it is--it
          will be in the way no matter what. If the boat did not have a
          tunnel, I would have no problem lowering the shaft angle in a slow
          speed craft--but in this case I would hesitate to change it by very
          much. The River Belle already has a very shallow shaft angle--I
          don't think you will gain much if any efficiency by lowering it more
          but doing so may throw off the performance of the tunnel. Good luck,
          Tom

          --- In AtkinBoats@yahoogroups.com, "Alan Boman" <alan@...> wrote:
          >
          > Hi Folks,
          >
          >
          >
          > The propeller shaft in River Belle has an upward angle of about
          6°.
          >
          >
          >
          > It would be convenient to have that nearer horizontal – does anyone
          have any
          > thoughts about what effect that change might have? (Remembering
          Atkin's
          > instructions about not changing anything!)
          >
          >
          >
          > Cheers
          >
          >
          >
          > Alan
          >
          >
          >
          >
          >
          > [Non-text portions of this message have been removed]
          >
        • Alan Boman
          Tom, Yes, you are right the aim is to lower the cabin sole. I am proposing to raise the sole (floor) level for a fair proportion of the length of the hull to
          Message 4 of 6 , Apr 7, 2008
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            Tom,



            Yes, you are right the aim is to lower the cabin sole. I am proposing to
            raise the sole (floor) level for a fair proportion of the length of the hull
            to create an aft saloon, and that requires the engine to be under the floor
            and the floor flat.



            The engine already has the sump (pan) and oil pump pickup modified so that
            it is very low profile, and that would allow me to reduce its highest point
            by 8 inches, which becomes significant – I’m just not sure if Mr William is
            rolling in his grave at the suggestion or not………



            Actually, I’m getting the sense that as my first tunnel stern, it may be
            better to leave the hull design well alone……………



            A





            -----Original Message-----
            From: AtkinBoats@yahoogroups.com [mailto:AtkinBoats@yahoogroups.com] On
            Behalf Of Tom Hesselink
            Sent: Saturday, 5 April 2008 7:31 AM
            To: AtkinBoats@yahoogroups.com
            Subject: [AtkinBoats] Re: Shaft angle



            Alan, The first question is why do you want to lower the shaft
            angle? Is it to get the motor under the cabin sole? That seems
            unlikely from what sketchs I can see on the web. Once the motor
            pojects into the cabin- it usually dosent matter how high it is--it
            will be in the way no matter what. If the boat did not have a
            tunnel, I would have no problem lowering the shaft angle in a slow
            speed craft--but in this case I would hesitate to change it by very
            much. The River Belle already has a very shallow shaft angle--I
            don't think you will gain much if any efficiency by lowering it more
            but doing so may throw off the performance of the tunnel. Good luck,
            Tom

            --- In AtkinBoats@yahoogro <mailto:AtkinBoats%40yahoogroups.com> ups.com,
            "Alan Boman" <alan@...> wrote:
            >
            > Hi Folks,
            >
            >
            >
            > The propeller shaft in River Belle has an upward angle of about
            6°.
            >
            >
            >
            > It would be convenient to have that nearer horizontal – does anyone
            have any
            > thoughts about what effect that change might have? (Remembering
            Atkin's
            > instructions about not changing anything!)
            >
            >
            >
            > Cheers
            >
            >
            >
            > Alan
            >
            >
            >
            >
            >
            > [Non-text portions of this message have been removed]
            >





            [Non-text portions of this message have been removed]
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